AK Design Collaborative - Insignia-Class Economy Speakers (a.k.a Indignia)

[RayW]

Does the T-amp drive them well enough for dorm, iPod, or computer use?

As long as you're realistic about it.

I think part of the midrange ring I had in the shop may have been the T-amp distorting because I had it pretty much cranked up. Granted, they were set up on the B&D Workmate, pointing out the garage door and I was standing about 10' back from them. A tough venue for any small setup.

It would work very well for a computer system and would be a good dorm system as long as you don't try to out thump the guy next door with the subs.

Ray

 

[YamahaFreak]

As long as you're realistic about it.

I think part of the midrange ring I had in the shop may have been the T-amp distorting because I had it pretty much cranked up. Granted, they were set up on the B&D Workmate, pointing out the garage door and I was standing about 10' back from them. A tough venue for any small setup.

It would work very well for a computer system and would be a good dorm system as long as you don't try to out thump the guy next door with the subs.

Ray

That's why you get your own sub.

 

[Robie]

Zilch,

Lots of questions so thanks for the patience.

1. Is that a pic of all the components that comprise Version 3.5 or is that 3.6?
2. Also, could you please tell us what we are seeing in the the graph you posted along with the new xover components pic.
3. What version does the graph depict?
4. Do I have it right that you have designed/modeled version 3.5 but not measured/installed it yet?

Lastly, it appears there is a RayW mod to version 3.5 as I understand it. He evidently substituted an air core inductor for the iron core you specified in version 3.5 and perhaps depict in the pic. He also seems to have inserted an 8 ohm resistor in the tweeter circuit vs. the 7 ohm you specified in version 3.5. Minimal effect on cost.

5. Does this make Ray's xover Version 3.6?

I've got my credit card in hand and ready to order speakers and xover parts as soon as there is consensus on the design.

Thanks for putting up with my plodding questions.

 

[Zilch]

Zilch,

Lots of questions so thanks for the patience.

1. It's all of the components for 3.5, from sponsor Parts Express.

2. That's the measured impedance of the speakers. It only drops below 8 Ohms in a narrow range, 6.5 Ohms minimum. There are no wild impedance swings, so tubes should like them as well as SS amps. Ray might comment further, as he's more familiar with typical commercial products.

Compare to that of the original Advents here:

http://audiokarma.org/forums/showthread.php?p=1941709#post1941709

3. It's my prototype V3.5s. Both are shown. They superimpose for most of the range.

4. No. I'm running V3.5 for some time now, since I first measured it here 6/20/08.

4.5 Ray used some substitute components he had on hand for his build. It's the same V3.5 design.

5. No. Not substantive, just substitutes.

Hang on a couple of more days. Ray'll either give us a "Go," or a "Change this; better...."

 

[RayW]

Ray, how do they compare to your dayton RS180/morel tweeter creation?

Ok Dave. Had to run some more speaker wire and crawl around behind the system the Indignias are running on right now. Been switching back and forth this evening. The Indignias compare very favorably. If you recall, the RS/Morel things got prematurely "finished" when my laptop melted down and I lost my measurement system. I still need to do some tweaking around there. However, I can say a few things:

-The Indignias don't have quite the bass that the RS180's will put out. Understandable as it's a slightly bigger speaker and I have them in a bigger enclosure. Having said that, the Indignias have a lot more bottom end than they have a right to.

-The Morel tweeter has a bit more "air" about it. I haven't compared graphs but the Morel seems to have more sizzle. Note: I had to throw a shelf filter on the Morels to keep my ears from bleeding so they still may be a little hot.

-Overall and as of right now the Indignias are better balanced top to bottom than the RS/Morel.

-I could sit and listen to either without a problem.

Bob, if Z doesn't post something in English then tomorrrow I'll do a tutorial on the graphs he put up.

Ray

 

[Robie]

Thanks, Zilch. You can probably feel the lack of patience on my part, but I'll defer to you DIYmeisters.

Think I understand the graph. Both traces seem to be doing parallel things. The blue is impedence and the gold phase?

Ray, was trying to give you your Birthday off. Hope you had a good one.

 

[Zilch]

Red is the impedance.

I should have turned the blue phase curve off, 'cause I don't understand it.

[Ray'll tell us what it's about now, tho.... ]

 

[RayW]

[Ray'll tell us what it's about now, tho.... ]

Uh, thanks Zilch.

The pertinent things to notice on the impedance curve are:

-the minimum, which looks to be about 6.5ohm...pretty benign.
-you can see the resonant frequencies of the drivers at 65-70 (hard to call with a dual trace/fat line) and ~1100
-The minimum between the 2 low peaks is the actual tuning frequency of the box whic looks to be about 39 or so.

Phase...hmmm, that one's hard to explain. Let's try this...the phase is a measure of the slope of the SPL curve. So if the SPL is flat then the phase is 0. If the SPL suddenly goes up then the phase is positive. The higher the slope of the upward trend in SPL, the higher the phase. So looking at the phase can give an idea of the "flatness" of the SPL. If the phase stays close to 0 then you have a pretty flat SPL curve. If the phase gets really big then you have a sharp bump in the SPL. People tend to be able to hear sharp bumps in frequency response.

Note: what we're looking at on this particular graph is the phase of the impedance and I'm not sure it has any real meaning. I'm just trying to define what the phase is in general and where it can be useful.

Ray

 

[Zilch]

I provided Indignia V3.5 response phase @ #311, both normal (Blue) and minimum (Green):

http://audiokarma.org/forums/attachment.php?attachmentid=96966&d=1214610993

Observations, please, Ray? I think it's quite good, particularly through the 2 kHz crossover region....

 

[RayW]

I provided Indignia V3.5 response phase @ #311, both normal (Blue) and minimum (Green):

http://audiokarma.org/forums/attachment.php?attachmentid=96966&d=1214610993

Observations, please, Ray? I think it's quite good, particularly through the 2 kHz crossover region....

I would guess that with it falling off fairly constantly like that that the (electrical/acoustic) distance to microphone is off a little. If there's a constant delay then the phase will change with frequency like that. Having said that, it's a fairly constant rolloff with no big hiccups which means it looks good to me. With a system that measures true phase like a TEF20 you can get that stuff set pretty easily. With one that derives phase it can be a pain so I usually don't mess with it much. Just watch around the crossover like you said. With no problems showing, I move on.

Ray

 

[Zilch]

Just watch around the crossover like you said. With no problems showing, I move on.

Yes, I saw the straight line through 2 kHz, and said, "Ship it...." :thmbsp:

 

[Robie]

Gentlemen,
I believe I have compiled the parts lists (w/o cabinets) based on the posts above.

Edit: Costs for speakers are based on sale pricesthat end come August. Also, no binding posts included.

 

[Zilch]

You have different prices for the same L2.

8-Ohm R-1 is P/N 004-8.

Input terminals (optional) P/N 091-1245/6/7

 

[Robie]

Corrected spreadsheet in post 352. Thanks Zilch.

EDIT: Reflects speaker sale prices and still left the binding posts off, though.

 

[RayW]

Ok, got a little measuring done. I'm still climbing up the learning curve on SoundEasy. The comb filter looking stuff is, as far as I can tell, from the 7' tall room and I can't manage to pad the ceiling. I'll try dragging everything outside and see if it goes away. Not tonight though.

Anyway, overlooking the bobbles there, it looks like my 8ohm resistor is pulling the tweeter down too much so I'll dig around in the shop and see what I can find. I have several old commercial proto crossovers with resistors that I could scavenge but I don't remember what their values are. May have to make a trip to RS and see if they happen to have what I need. Otherwise I'll be looking for more stuff to make up another PE order. They have a laid back sound with the tweeter down like that so if somebody is into the "east coast" thing this might be the way to go.

Oh yeah, this is just far field so everything below about 300Hz is meaningless.

Ray

 

[Zilch]

Is that "In-room" response, Ray?

If so, it's looking pretty good, I'd say:

Stereophile dubbed this in-room response measurement of JBL K2-S9800 "Exemplary":

 

[Robie]

The FR graph Zilch posted at #311 shows a slight up tilt as frequencies increase.

Ray's mod has them falling a bit (even though they seem to resemble some highly desirable curves).

So the goal is some where between the two?

That said, I listened to the Insignias for a while last night (with my old MA230 integrated). Pretty rolled off sound, particularly off axis. But very pleasant and non-fatiguing. Switched to my larger EPI 70Cs (refoamed, recapped and bypass capped). Totally different sound that sounded much more open and airy. Tighter bass too.

Zilch, do you have a curve for unmodded Insignias?

 

[RayW]

Is that "In-room" response, Ray?

Yeah, in room at 1m MLS. When I get a chance I'll do an outside too but my wife has hijacked my laptop so I'll have to work it out for when she's home. She's doing CME (continuing medical education) and takes precedence.

Bob, as mine stands the highs are a little subdued. You don't really notice it unless you listen to them A/B with something that has more zing. I usually pull the highs down a little on my designs as it makes them easy to listen to for a long while. Grab somebody who heard my MTM TL's at the fest and ask them about it. I wish I could remember who I was talking to at that time but there was someone who asked about it and I explained my reasoning. About 3 songs later he said "I see what you mean" with a smile.

Anyway, I'll try to dig up a pair of 7ohm resistors and maybe a pair of 6 just to play around and see what they sound like.

Ray

 

[tgunner]

Has anyone here ever seen a tri-angle speaker design? I just drew this up quickly in paint.

 

[Zilch]

The FR graph Zilch posted at #311 shows a slight up tilt as frequencies increase.

Ray's mod has them falling a bit (even though they seem to resemble some highly desirable curves).

So the goal is some where between the two?

My curves are quasi-anechoic. A flat anechoic curve yields a downward-sloping "in-room" response. Ray's curve is more representative of what we actually hear; we don't listen in an anechoic environment, typically, but outdoors with no boundaries or reflections approximates one.

Ray is suggesting that Indignias may be "voiced" to taste by varying R1. I measured the effect of different values in 1-Ohm increments between 6 and 10 Ohms here, also @ #311:

http://audiokarma.org/forums/attachment.php?attachmentid=96967&d=1214610993

Zilch, do you have a curve for unmodded Insignias?

I've never had any to measure, but Murphy, Zaph, and a couple of others who worked out mods for them have all posted "before" curves.

Has anyone here ever seen a tri-angle speaker design?

Yes, but they're not very common. It has the advantage of non-parallel walls reducing standing waves inside the box. AR "Powered Partners" come to mind.

If you look at the curved-side designs I've posted earlier in this thread, they're really triangular in the horizontal plane, truncated at the rear into trapezoids, a less extreme aesthetic having much the same benefit.

You gonna build some triangle Indignias, Tgunner? Just calculate your dimensions to approximate the 0.38 cuft design interior volume, and it'll work.... :thmbsp: